Semi-frequent ECONNRESET from sidecar proxy (TCP proxy) when upstream has response

We have been experiencing semi frequent connection resets from the sidecar proxy. The upstream (external) has received the request but we are not able to get a response, this is causing havoc in our applications because we try to retry ECONNRESET’s, where without the proxy are safe to retry.

Attached are two screenshots, one a tcpdump showing the exchange of packets, and the other envoy connection +connection pool logs in trace mode. There are 3 concurrent requests that came back normally around the same time as this request and it appears to have responded with data, but the proxy can’t forward to the downstream app (Node JS 8). We’re running Istio 1.4.